The present invention relates to a portion capsule for producing a beverage, having a capsule body with a capsule base and a filling side, wherein a cavity for accommodating a pulverulent or liquid beverage base is formed between the capsule base and the filling side, and wherein a filter element is arranged between the beverage base and the capsule base.
Portion capsules of this kind are generally known from the prior art. By way of example, documents EP 1792850 B1, EP 1344722 A1 and US 2003/0172813 A1 disclose portion capsules of this generic type for preparing coffee and espresso.
Portion capsules of this kind for producing a beverage are preferably in the form of a truncated cone or cylinder and are produced, for example, from a thermoformed plastic film or using a plastic injection molding process. Said portion capsules usually have an open filling side with a collar edge onto which a cover film or foil is sealed or adhesively bonded, a closed capsule base, with a particle screen which is supported against the capsule base being arranged between the beverage base and the capsule base. These screens are either injection molded from a thermoplastic or are thermoformed or stamped from a plastic film.
For the purpose of preparing a coffee beverage, the portion capsule is inserted into a brewing chamber of a preparation appliance. After or during the closing process of the brewing chamber, the capsule is preferably opened on its closed base side by means of a discharge mandrel which is arranged in the brewing chamber and, after the brewing chamber is sealed off, the filling side of the portion capsule, which filling side is sealed off by a sealing film or foil, is tapped by means of a puncturing means. Preparation liquid, preferably hot water, is then delivered into the portion capsule under pressure. The preparation liquid flows through the beverage base and extracts and/or dissolves the substances, which are required for producing the beverage, from the beverage base. For the purpose of preparing an espresso, for example a brewing water pressure of up to 20 bar acts on the coffee powder for the purpose of extracting the essential oils. This pressure also acts on the filter medium which is situated between the coffee powder and the capsule base and in front of the punctured capsule outlet.
The sudden pressure loss on the lower face of the filter medium leads to the formation of froth in the beverage, for example in the form of a crema of a coffee beverage. However, the formation of froth is undesirable for certain beverages, for example a classic filter coffee without crema which is consumed in the USA and Scandinavia.
Therefore, the object of the present invention was to provide a portion capsule having a filter arrangement, in which the level of the formation of froth achieved is reduced in comparison to the prior art to virtually zero or in which the formation of froth is entirely avoided, even when the portion capsule is extracted in a high-pressure extraction machine.